1. Field of the Invention
The present invention relates to an information processing apparatus, control method thereof, and storage medium and, more particularly, to an information processing apparatus which generates a recognizer for recognizing a work subject and estimates the three dimensional positions and orientations of piled work subjects using the generated recognizer in order to perform predetermined work with a robot
2. Description of the Related Art
In the field of recognition using visual information, various researches and developments have been made in regard to a method of estimating the three dimensional position and orientation of a subject. In the field of industrial robots or experimental humanoid robots, three dimensional information is often used for the purpose of random picking and the like, and its necessity is growing. When the orientation of a target subject to be handled has a high degree of freedom, various orientations of the target subject need to be estimated three-dimensionally. As for a target subject with a known shape, its position and orientation are estimated using a three dimensional sensor such as a stereo camera or laser range finder. The correspondence between a three dimensional feature amount obtained from the three dimensional sensor and a three dimensional feature amount regarding a plurality of feature points on a model is obtained. Then, the position and orientation of the subject are calculated using rigid transformation. The position and orientation of a target subject are also estimated using a monocular camera. There is a method of recognizing various orientations as a multi-class classification problem.
Even if a target subject has a three dimensional degree of freedom, it may suffice to recognize only restricted orientations for practical use. In gripping work for a target subject with a robot hand, a detected target subject in an estimated orientation may not be able to be gripped owing to the relative positional relationship with the robot. A task to detect such a target subject is wasteful and can be ignored from the beginning without any problem. Especially in the field of industrial robots, this restriction is often essential. Taking the trouble to detect a target subject in an orientation incapable of gripping increases the memory capacity and prolongs the detection processing time in a recognizer used for detection.
In Japanese Patent No. 2555823, when collating parts based on the contours of images of piled parts, a collation limit value indicating a mismatch range permitted for a collation model in a reference orientation is set based on a tolerance limit angle in a grippable range. This method does not set a high degree of freedom of the orientation, and a target subject is detected by relaxing the collation limit value from one reference orientation to permit variations of the orientation from the reference orientation.
The method disclosed in Japanese Patent No. 2555823 takes account of an orientation range considering grippability, but does not examine a case in which the degree of freedom of the orientation is high. Further, it is difficult to apply this method when the appearance of a target subject greatly changes depending on the orientation.
In consideration of the aforementioned problems, the present invention provides a technique of reducing the memory capacity of a recognizer used in actual work for a target subject with a high degree of freedom of the orientation, and shortening the recognition processing time when detecting a target subject.